I'll send my feedback here but consider that it belongs to all
the 3 passthrough related patches you've sent.

Testing in my TP, with your patches, I had one extra error
when switching to the 'To Add' filter. In current master I have
the following error:
With your patch:
There's an extra error 'Node device undefined not found'.

Ideally you could get rid of all the errors in this window but at the
very least we can't increase them.
On 07/27/2016 11:00 PM, Jose Ricardo Ziviani wrote:
 - In order to validade if a given PCI is ok to be attached, a heavy
   verification has to be done. This commit add such verification
   in the task. This will give a faster response to the UI,
   improving the user experience.

Signed-off-by: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
---
 model/vmhostdevs.py                 | 22 ++++++++++++++++-
 ui/js/src/kimchi.guest_edit_main.js | 47 ++++++++++++++++++++-----------------
 2 files changed, 47 insertions(+), 22 deletions(-)

diff --git a/model/vmhostdevs.py b/model/vmhostdevs.py
index 15b5bec..ef39de3 100644
--- a/model/vmhostdevs.py
+++ b/model/vmhostdevs.py
@@ -89,7 +89,6 @@ class VMHostDevsModel(object):
 
     def create(self, vmid, params):
         dev_name = params['name']
-        self._passthrough_device_validate(dev_name)
         dev_info = self.dev_model.lookup(dev_name)
 
         if dev_info['device_type'] == 'pci':
@@ -216,6 +215,13 @@ class VMHostDevsModel(object):
         dev_info = params['dev_info']
         lock = params['lock']
 
+        try:
+            self._passthrough_device_validate(dev_info['name'])
+
+        except InvalidParameter as e:
+            cb(e.message, False)
+            raise
+
         with lock:
             try:
                 self._validate_pci_passthrough_env()
@@ -455,6 +461,13 @@ class VMHostDevsModel(object):
         dev_info = params['dev_info']
         lock = params['lock']
 
+        try:
+            self._passthrough_device_validate(dev_info['name'])
+
+        except InvalidParameter as e:
+            cb(e.message, False)
+            raise
+
         with lock:
             dom = VMModel.get_vm(vmid, self.conn)
 
@@ -501,6 +514,13 @@ class VMHostDevsModel(object):
         dom = VMModel.get_vm(vmid, self.conn)
         lock = params['lock']
 
+        try:
+            self._passthrough_device_validate(dev_info['name'])
+
+        except InvalidParameter as e:
+            cb(e.message, False)
+            raise
+
         with lock:
             with RollbackContext() as rollback:
                 xmlstr = self._get_usb_device_xml(dev_info)
diff --git a/ui/js/src/kimchi.guest_edit_main.js b/ui/js/src/kimchi.guest_edit_main.js
index 507ae75..5d91b14 100644
--- a/ui/js/src/kimchi.guest_edit_main.js
+++ b/ui/js/src/kimchi.guest_edit_main.js
@@ -546,9 +546,11 @@ kimchi.guest_edit_main = function() {
                     wok.message.error(err.responseJSON.reason, '#alert-modal-container');
                 });
             } else {
+                $('html').addClass('in-progress');
+                $('#form-guest-edit-pci > .wok-mask').show();
+                var haveCompanions = false;
+                var pciTitle = i18n['KCHVMED6007M'] + '\n';
                 kimchi.getPCIDeviceCompanions(id, function(infoData) {
-                    var pciTitle = i18n['KCHVMED6007M'] + '\n';
-                    var haveCompanions = false;
                     for (var p = 0; p < infoData.length; p++) {
                         if (infoData[p].device_type === 'net') {
                             haveCompanions = true;
@@ -564,24 +566,19 @@ kimchi.guest_edit_main = function() {
                             pciTitle += ', ' + i18n['KCHVMED6006M'] + ' ' + infoData[p].model + '\n';
                         }
                     }
-                    var settings = {
-                        title: i18n['KCHVMED6012M'],
-                        content: pciTitle,
-                        confirm: i18n['KCHAPI6002M'],
-                        cancel: i18n['KCHAPI6003M']
-                    };
+                });
+                $('#form-guest-edit-pci > .wok-mask').fadeOut(300, function() {});
+                $('html').removeClass('in-progress');
 
-                    if (haveCompanions) {
-                        wok.confirm(settings, function() {
-                            kimchi.addVMPCIDevice(kimchi.selectedGuest, {
-                                name: id
-                            }, function(task) {
-                                getOngoingAttachingDevices(task);
-                            }, function(err) {
-                                wok.message.error(err.responseJSON.reason, '#alert-modal-container');
-                            });
-                        });
-                    } else {
+                var settings = {
+                    title: i18n['KCHVMED6012M'],
+                    content: pciTitle,
+                    confirm: i18n['KCHAPI6002M'],
+                    cancel: i18n['KCHAPI6003M']
+                };
+
+                if (haveCompanions) {
+                    wok.confirm(settings, function() {
                         kimchi.addVMPCIDevice(kimchi.selectedGuest, {
                             name: id
                         }, function(task) {
@@ -589,8 +586,16 @@ kimchi.guest_edit_main = function() {
                         }, function(err) {
                             wok.message.error(err.responseJSON.reason, '#alert-modal-container');
                         });
-                    }
-                });
+                    });
+                } else {
+                    kimchi.addVMPCIDevice(kimchi.selectedGuest, {
+                        name: id
+                    }, function(task) {
+                        getOngoingAttachingDevices(task);
+                    }, function(err) {
+                        wok.message.error(err.responseJSON.reason, '#alert-modal-container');
+                    });
+                }
             }
         });
     };